Simplify devpts_pty_kill

When creating a new pty, save the pty's inode in the tty->driver_data.
Use this inode in pty_kill() to identify the devpts instance. Since
we now have the inode for the pty, we can skip get_node() lookup and
remove the unused get_node().

TODO:
	- check if the mutex_lock is needed in pty_kill().

Signed-off-by: Sukadev Bhattiprolu <sukadev@us.ibm.com>
Signed-off-by: Alan Cox <alan@redhat.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

1 files changed, 12 insertions, 17 deletions

diff --git a/fs/devpts/inode.c b/fs/devpts/inode.c
index 50e885f84bb0..a70d5d0890c7 100644
--- a/fs/devpts/inode.c
+++ b/fs/devpts/inode.c
@@ -170,14 +170,6 @@ static struct file_system_type devpts_fs_type = {
  * to the System V naming convention
  */
 
-static struct dentry *get_node(int num)
-{
-        char s[12];
-        struct dentry *root = devpts_root;
-        mutex_lock(&root->d_inode->i_mutex);
-        return lookup_one_len(s, root, sprintf(s, "%d", num));
-}
-
 int devpts_new_index(struct inode *ptmx_inode)
 {
         int index;
@@ -235,6 +227,7 @@ int devpts_pty_new(struct inode *ptmx_inode, struct tty_struct *tty)
         inode->i_mtime = inode->i_atime = inode->i_ctime = CURRENT_TIME;
         init_special_inode(inode, S_IFCHR|config.mode, device);
         inode->i_private = tty;
+        tty->driver_data = inode;
 
         sprintf(s, "%d", number);
 
@@ -262,18 +255,20 @@ struct tty_struct *devpts_get_tty(struct inode *pts_inode, int number)
 
 void devpts_pty_kill(struct tty_struct *tty)
 {
-        int number = tty->index;
-        struct dentry *dentry = get_node(number);
+        struct inode *inode = tty->driver_data;
+        struct dentry *dentry;
 
-        if (!IS_ERR(dentry)) {
-                struct inode *inode = dentry->d_inode;
-                if (inode) {
-                        inode->i_nlink--;
-                        d_delete(dentry);
-                        dput(dentry);
-                }
+        BUG_ON(inode->i_rdev == MKDEV(TTYAUX_MAJOR, PTMX_MINOR));
+
+        mutex_lock(&devpts_root->d_inode->i_mutex);
+
+        dentry = d_find_alias(inode);
+        if (dentry && !IS_ERR(dentry)) {
+                inode->i_nlink--;
+                d_delete(dentry);
                 dput(dentry);
         }
+
         mutex_unlock(&devpts_root->d_inode->i_mutex);
 }